In Molisch test, why does the concentrated acid need to be poured slowy?

Question

Please explain to me in detail.

Answer 1

Molisch's Test is a chemical test for the presence of carbs (sugars= monosaccharides, disaccharides,polysaccharides), based on the dehydration of the carb by sulfuric acid.
The test solution is combined with a small amount of concentrated sulfuric acid and is slowly added down the sides of the sloping test tube, without MIXING!! If the acid is poured too quickly, it results in a mixing of the contents and, can cause the test results to be inaccurate. All carbs and even, Glycoproteins will give a positive reaction. A positive reaction is indicated by a purple ring forming at the interface between the acid and test layers.The sulfuric acid needs to be slowly poured so that it can have time to get into the test layers. It enhances the depth perception of the reaction. I hope this is useful.

Answer 2

To prevent mixing of the acid with the Molisch solution. The acid acts on aldehydes to give a purple colour at the interface of the two solutions. If they were to mix, the layer of reaction would be more dispersed and less distinct. Layering gives a sharper colour.

Answer 3

I'm not sure about the Molisch test, but in general you pour acid slowly to prevent splattering, especially in a reaction.

I think, according to this (http://en.wikipedia.org/wiki/Molisch's_test) also to prevent mixing.

Hope that helps.